human herpesvirus 6

Human herpesvirus 6 (HHV-6) is a common virus that infects most people during childhood, often causing a mild illness called sixth disease or roseola, characterized by a sudden high fever and a rash. After initial infection, the virus stays dormant in the body for life. In some cases, HHV-6 can reactivate, especially in individuals with weakened immune systems, leading to health issues such as encephalitis or complications in transplant recipients. While usually harmless in healthy individuals, HHV-6 is an example of a virus that can persist silently and sometimes cause disease under specific conditions.